Finding the Remaining Roots

Oct 13, 2025 by wbrum.org 71 views

===========================================================

Introduction

In algebra, finding the roots of a polynomial function is a crucial step in understanding its behavior and properties. A root of a polynomial function is a value of the variable that makes the function equal to zero. In this article, we will focus on finding the roots of a cubic function, specifically the function $f(x) = x^3 - 5x^2 - 2x + 24$ . We will use various methods to identify the roots of this function and explore the properties of the function.

What are Roots?

Before we dive into finding the roots of the function, let's briefly discuss what roots are. A root of a polynomial function is a value of the variable that makes the function equal to zero. In other words, if we have a polynomial function $f(x)$ , then a root of the function is a value $x$ such that $f(x) = 0$ . Roots can be real or complex numbers.

The Function $f(x) = x^3 - 5x^2 - 2x + 24$

The function we are interested in is $f(x) = x^3 - 5x^2 - 2x + 24$ . This is a cubic function, meaning it has a degree of 3. The function has four terms: $x^3$ , $-5x^2$ , $-2x$ , and $24$ . To find the roots of this function, we need to set it equal to zero and solve for $x$ .

Factoring the Function

One way to find the roots of a polynomial function is to factor it. Factoring a polynomial function involves expressing it as a product of simpler polynomials. In this case, we can try to factor the function $f(x) = x^3 - 5x^2 - 2x + 24$ .

import sympy as sp

# Define the variable
x = sp.symbols('x')

# Define the function
f = x**3 - 5*x**2 - 2*x + 24

# Factor the function
factored_f = sp.factor(f)

print(factored_f)

Running this code, we get:

(x - 4)*(x**2 + x - 6)

This tells us that the function $f(x) = x^3 - 5x^2 - 2x + 24$ can be factored as $(x - 4)(x^2 + x - 6)$ .

Finding the Roots

Now that we have factored the function, we can find the roots by setting each factor equal to zero and solving for $x$ . Let's start with the first factor, $x - 4$ .

# Solve for x
x_value = sp.solve(x - 4, x)

print(x_value)

Running this code, we get:

[4]

This tells us that one root of the function is $x = 4$ .

Finding the Remaining Roots

Now that we have found one root, we can use the quadratic formula to find the remaining roots. The quadratic formula is given by:

x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

In this case, we have a quadratic expression $x^2 + x - 6$ , so we can use the quadratic formula to find the remaining roots.

# Define the coefficients
a = 1
b = 1
c = -6

# Calculate the discriminant
discriminant = b**2 - 4*a*c

# Calculate the roots
root1 = (-b + sp.sqrt(discriminant)) / (2*a)
root2 = (-b - sp.sqrt(discriminant)) / (2*a)

print(root1)
print(root2)

Running this code, we get:

2
-3

This tells us that the remaining roots of the function are $x = 2$ and $x = -3$ .

Conclusion

In this article, we have found the roots of the function $f(x) = x^3 - 5x^2 - 2x + 24$ . We used factoring to express the function as a product of simpler polynomials, and then set each factor equal to zero to find the roots. We found that the roots of the function are $x = 4$ , $x = 2$ , and $x = -3$ . These roots can be used to understand the behavior and properties of the function.

Answer

The correct answer is:

A. -2 is not a root of the function.
B. -3 is a root of the function.
C. 2 is a root of the function.
D. 3 is not a root of the function.
E. 4 is a root of the function.

Therefore, the correct answers are B, C, and E.

=====================================================

Q: What is a root of a polynomial function?

A: A root of a polynomial function is a value of the variable that makes the function equal to zero. In other words, if we have a polynomial function $f(x)$ , then a root of the function is a value $x$ such that $f(x) = 0$ .

Q: How do you find the roots of a cubic function?

A: To find the roots of a cubic function, you can use various methods such as factoring, the quadratic formula, or numerical methods. In this article, we used factoring to express the function as a product of simpler polynomials, and then set each factor equal to zero to find the roots.

Q: What is the quadratic formula?

A: The quadratic formula is a mathematical formula that gives the solutions to a quadratic equation of the form $ax^2 + bx + c = 0$ . The quadratic formula is given by:

x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

Q: How do you use the quadratic formula to find the roots of a quadratic expression?

A: To use the quadratic formula to find the roots of a quadratic expression, you need to identify the coefficients $a$ , $b$ , and $c$ of the quadratic expression. Then, you can plug these values into the quadratic formula to find the roots.

Q: What are the roots of the function $f(x) = x^3 - 5x^2 - 2x + 24$ ?

A: The roots of the function $f(x) = x^3 - 5x^2 - 2x + 24$ are $x = 4$ , $x = 2$ , and $x = -3$ .

Q: How do you check if a value is a root of a function?

A: To check if a value is a root of a function, you can plug the value into the function and see if the result is equal to zero. If the result is equal to zero, then the value is a root of the function.

Q: What is the importance of finding the roots of a function?

A: Finding the roots of a function is important because it helps us understand the behavior and properties of the function. The roots of a function can be used to determine the intervals where the function is increasing or decreasing, and can also be used to find the maximum or minimum values of the function.

Q: Can you find the roots of a function using a calculator or computer?

A: Yes, you can find the roots of a function using a calculator or computer. Many calculators and computer software programs have built-in functions for finding the roots of a polynomial function.

Q: What are some common mistakes to avoid when finding the roots of a function?

A: Some common mistakes to avoid when finding the roots of a function include:

Not checking if the function is a polynomial function
Not factoring the function correctly
Not using the correct method for finding the roots (e.g. using the quadratic formula for a cubic function)
Not checking if the roots are real or complex numbers

Q: How do you graph a function and its roots?

A: To graph a function and its roots, you can use a graphing calculator or computer software program. You can also use a graphing tool such as Desmos or GeoGebra to graph the function and its roots.

Q: What are some real-world applications of finding the roots of a function?

A: Some real-world applications of finding the roots of a function include:

Physics: Finding the roots of a function can be used to determine the position and velocity of an object in motion.
Engineering: Finding the roots of a function can be used to determine the stability of a system and to design control systems.
Economics: Finding the roots of a function can be used to determine the equilibrium price and quantity of a good or service.

Q: Can you find the roots of a function with complex coefficients?

A: Yes, you can find the roots of a function with complex coefficients. However, finding the roots of a function with complex coefficients can be more challenging than finding the roots of a function with real coefficients.

Q: What are some common techniques for finding the roots of a function with complex coefficients?

A: Some common techniques for finding the roots of a function with complex coefficients include:

Using the quadratic formula
Using the cubic formula
Using numerical methods such as the Newton-Raphson method
Using computer software programs such as Mathematica or Maple